Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2012	Dec. 31, 2011
Accumulated amortization on deferred financing and leasing costs	$ 128,303,000	$ 123,822,000
Common shares, par value	$ 0.001	$ 0.001
Common shares, shares authorized	183,987,000	183,987,000
Common shares, shares issued	118,264,957	117,352,353
Common shares, shares outstanding	118,264,957	117,352,353
Treasury stock, shares	1,249,909	1,249,909
Noncontrolling Interest Operating Partnership Common Units Outstanding	3,808,746	3,808,746
Preferred stock, units outstanding	5,290,000	9,740,000
Liberty Property Limited Partnership [Member]
Accumulated amortization on deferred financing and leasing costs	$ 128,303,000	$ 123,822,000
Common shares, shares outstanding	117,015,048	116,102,444
Treasury stock, shares	1,249,909	1,249,909
Preferred stock, units outstanding	5,290,000	9,740,000
Limited Partners' Capital Account, Units Issued	3,808,746	3,808,746
Series I-2 [Member]
Preferred stock, units outstanding	301,483	301,483
Series I-2 [Member] | Liberty Property Limited Partnership [Member]
Preferred stock, units outstanding	301,483	301,483